At present, in an image signal processing procedure, generally, the resolution of an image can be raised by means of the standard methods such as a bicubic upsampling process and a linear upsampling process (for enlarging image resolution). As illustrated in FIG. 1, a 2× upsampling mode is shown, four different filters: filter F1, filter F2, filter F3 and filter F4, are applied to all the pixels (plus adjacent pixels) of an input image, each filter generates a quarter of the pixels of the output image, and the process may be understood as applying four filters (convolution) to the input image, and then interleaving or multiplexing to create a single output image that doubles the width and the height of the image.
However, data computation amount of the current image upsampling system is relatively large, and the upsampling multiple (times) cannot be flexibly adjusted.